Group selection control circuit



July 17, 1951 M. DEN HER'roG GROUP SELECTION CONTROL CIRCUIT 2 Sheets-Sheet l Filed June 12, 1950 l M II-Inventor MARTINI/5 DEN HEFm By Z Attorney;

July 17, 1951 M. DEN HERTOG GROUP SELECTION CONTROL CIRCUIT 2 Sheets-Sheet 2 Filed June 12, 1950 QQ\ I bb IIIIVL y :Q ll'lllnlllllnklallrlll* In ventor MART/N05 DEN HETO@ Attorney Patented July 17, 1951 GROUP SELECTION CONTRL CIRCUIT Martinus 4den .Hertog, Antwerp, Belgium, assignor rto International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application June 12, 1950,:Serial No. 'IE7-,67.2 In France June 2, y1949 `s claims. (crm- 353) The present invention relates to a scanning system which in particular makes it possible to .select ra circuit from one or more groups of circuits, the scanning operation being effected by Ysimplemeans andin an extremely short time.

One of the features of theinvention is the emiployment of static electrical means in order automatically to test the-electrical condition of a plurality of `circuitsto which said static means have access -and to effect a selection of one circuitina vparticular group of said circuits.

.Another characteristic Aof .the invention is the testing in a predeterminedorder -by static elec-- 4trical means of afcertain number of circuits divided up `into several groups, arrangements being ,providedfor controlling the order of scanning of the circuits, for proceeding successively with the identity testing of each of the circuits in terms of the vgrouping-of said circuits, and for testing the electrical condition of the circuits.

Another characteristic of the invention con sists in a system for-scanning one or more groups of circuits and selecting one circuit in aparticular group, andfor recording theidentity of the selected circuit, and for effecting, under the control of the registering device, the operations of `connection of the selected circuit.

Another feature of the invention consists of a selection system for selecting one circuit in one or more groups of circuits, in which several stages of time positioned control impulses are employed to control thescanning.

Another characteristic ofthe invention consists .of a device for selecting one vcircuit in a set of groups of circuits and comprising a group of elec- 'trical switches, the number of said electrical "switches being equal .to the maximum number of circuits in [a group and their arrangement 'being provided on the one handin order to control the 'selection of the group of circuits and on the other Vhand in order to control the .selection of one circuit in the. selected group.

Another 4characteristic of the invention 'consists 'of 'a device vfor selecting one circuit in a set of groups of circuits .and comprising a group of thermionic or gas discharge devices, each device comprising several electrodes, the number of devices in each group being equal to the maximum number of circuits in one group, and their arrangement being provided in order .on -the one hand to control :the selectionofthe `group of circuits and on the other .hand to control the selection of one circuit `in the selected group.

The essence of the invention and -various other characteristics will appear from the following description given as a non-limitative example with referenceto the attached drawings, in which:

Fig. 1 shows a selectioncontrol circuit comprising a group ofcold .cathode tubes for the purpose of selecting a free circuitin a certain ,nurnber of groups of circuits which may, for example,

-be the outlets of one selection stage in an automatic telephone exchange.

Fig. 2 shows the Vpotential impulse curves of Atwo different orders employed in the circuit arrangement of Fig. 1.

Referring to Fig. l, two groups of cold cathode tubes VaI to Va`3 and VbI to Vb3, have been provided, each 'comprising 'an anode, represented by a small circle, a .cathode connected through a l.contact cI or ce2 and 'a resistanceRl or R2 to the batteries BI or B2, each of these batteries being assumed to 'have a voltage of 150 v., and a control electrode connected to the signalling or marking wire MW.

It `hasbeen .assumed that the selection is to be made in a set of three groups of .circuits each comprising three circuits CII to CI3, C2I to C23 and C31 to C33. kThe circuit elements shown consist of the test Wires of the various circuits, in 'each of which is inserted a busy contact BCI I to BCI3, BC2I 110.13023, B'CSI to B033.

The test vwires of each of the first circuits in each group are connected through unidirectional current carrying devices, such as rectiers, for example, vRCI I., RC2I, RC3I to the common Wire IWI. Similarly, the test wires of the second circuits of the different groups are connected via'the rectiers RCIZ, RC22, R032 to the common wire IW2, while thetest Wires 'of the third circuits of 'the diierent jgroupsare connected via the recti- 3 described on the assumption that the wires IWI, IW2, IW3 are respectively connected to the Wires TWI, TW2, TW3.

The selection of a group of lines and the selection in the group of lines is entirely controlled by the group of tubes Vbl to Vb3. The purpose of the tubes Val to Va3 is to register the identity of a selected group of circuits by the operation of one of the tubes corresponding to the selected group. The tubes VbI to Vb3 are not only intended to control the selection but also to register the identity of the selected circuit in a selected group, and thus it is by the operation of the first, second or third tube which respectively corresponds to the first, second or third circuit of each of the groups.

In the anode circuit of each of the tubes a relay Ra or Rb is inserted; the relay RaI comprises the contact Ral I, relay Ra2 the contact Ra2l, relay Ra3 the contact Ra3l; relay RbI comprises the contacts RbII, RbIZ and Rbl3 and relay Rb2 comprises the contacts Rb2 I Rb22 and Rb23, and relay R193 the contacts Rb3I,v

Rb32 and Rb33. The combination of these different relay contacts makes it possible to apply earth to one of the wires I--9 corresponding to the three circuits of the three groups, in accordance with the group and line selected.

The various circuits among which the selection is to be operated, are characterized by time positioned impulses which are applied thereto. These impulses are repetitive impulses with a repetition rate which is the same for each circuit. The time duration of each impulse is short with respect to the time between impulses, and the impulses characterising each group of circuits are spaced in time from those characterizing any other group. These impulses are represented at I, e2, and q 3 in Fig. 2, and, as shown, produce potentials of volts during the period of the impulse, while the potential changes to -100 volts between impulses. These impulses are produced in a known manner by the threev generators indicated in Fig. l as pl generator, e2 generator, e3 generator. Potential impulses in accordance with a periodic cycle el, sp2, and p3, the number of impulses per cycle being equal to the number of groups of circuits, are applied to the test wires of the circuits from the impulse generators, each of the generators being assigned to a different group and the impulses thereof sent to each of the test wires in the group. Marking wire MW is connected at its end to a mobile or wiper contact sc in order selectively to connect said MW to one or the contacts PtI, Pt2 or Pt3 on which are also received the same potential impulses (pI, c2, and p3 used to mark the groups of circuits. These same impulses spl, e2, and p3 are also applied respectively to the control electrodes of the tubes Val, Va2, and Va3.

Another set of potential impulse generators labelled PI generator, P2 generator and P3 generator, in Fig. 1, producing repetitive impulses PI, P2, and P3 at a submultiple rate with respect to the rate of the impulses qu I, e2, and fp3 is also employed. Each of the impulses of these generators has a time duration equal to that of a complete cycle of impulses qvI, @2, and c3. In the simple selective system shown, these impulses repeat at one third the rate of the impulses (pl, e2, and m3; in other words there is one cycle for every three cycles of qaI, (p2, and (p3. The impulses PI, P2, and P3 are spaced in time with respect to each other, aswill be seen from Fig. 2,

and have a potential of -50 volts, while between impulses the potential is volts. The individual impulses PI, P2, and P3 are respectively applied to the control electrodes of the tubes Vbl, Vb2, Vb3.

It has been assumed that when a potential impulse is not sent, the potential of the source is 100 v.; under these conditions the potential applied to the control space of a tube is insufficient to cause it to be ionized, since the difference of potential between the cathode and the control electrode is only 50 v. At regular intervals, however, when the impulses are applied, the voltage of the control electrode may be raised to -50 volts making a difference of potential of 100 volts between the control electrode and the cathode. This potential can cause ionization of the tube if the contact ca: of its cathode is closed.

For the operation of the tubes Va and Vb the potentials of -100 v. are ineffective control potentials, while potentials of 50` v. are effective control potentials.

The connections to the control electrodes are not made directly, but through resistances and rectifiers. For each of the individual control electrodes a connection is made through a resistance, while any other connections are made through a rectifier or rectiiiers. Tube Val, for example, has its control electrode connected to the NW wire through rectifier Regal, while the qJI impulse is applied to this electrode through resistance RhaI Tube Va2 has its control electrode connected through rectifier RcgaZ to the MW wire and to the source of e2 impulses through resistance Rha2. Tube Va3 has its control electrode connected through rectifier Rcga3 to the MW wire and to the source of 'p3 impulses through resistance Rha3. Tube Vbl has its control electrode connected to the source of PI impulses through rectifier Rcubl, to the MW wire through rectifier Rcgbl, and to the TWI (or TW) wire through a resistance Rhbl. Tube Vb2 has its control elec'- trode connected to the source of P2 impulses through rectifier Rcub2, to the MW wire through rectifier Rcgb. and to the TW2 (or TW) wire through resistance Rhb2. Tube Vb3 has its control electrode connected to the source of P3 impulses through rectier Rcub3, to the MW wire through rectifier Rcgb3, and to the TW3 (or TW) wire through resistance RhbS.

The general rule for connections to control electrodes in that any number of impulse sources may be connected to each control electrode without mutual interference of the different sources and/or tubes, provided only that each of the control electrodes is connected to one source through a resistance and to all the others through a rectier peculiar to each of them. The source connected through the resistance acts as a source from which the current is supplied to effect an ionization of the discharge gap, the other sources which are connected to the same gap through rectifiers never supply current, but only absorb the current supplied by the source connected through the resistance during the time in which the potential of the latter is effective, and at least one of the absorbent sources ineffective. For this reason the rectifiers must be poled so as to permit current to flow through the resistance from the source connected thereto.

Assume that the potential applied to the resistance connected to the control electrode of a tube is -50 volts because at that instant the impulse from one of the sources is applied thereto. Then at that instant if the potential applied to the other terminal of one of the rectiflers connected to the same control electrode is -100 volts, which is the voltage from any of the sources at the time between impulses, then current will flow Vthrough the resistancevcausing the control electrode to assume a potential of -l00 volts and preventing the tiring `of the tube. If, however, the potential applied to the outside terminals of yall of the rectiers connected to the control electrode were 50 volts at this time, the rectiers lwould be blocked and no current could flow through the resistance. The control electrode would therefore have a voltage of -50 volts 'applied to it, and since there would then be a difference of 100 volts between the control electrode and the cathode the tube would re. In order for atube to iire, therefore, it must have -50 volts applied to the resistance and all rectiers connected to the control electrode. This can only happen when the impulses applied to the resistance and to all the rectifiers coincide.

Instead of three groups each of three circuits, ythere mightfbe anynumber of groups with any number of circuits as desired, for example, ten groups each of ten circuits, the Anumber of the tubes being provided accordingly, that is'to say, ten tubes Va and ten tubes Vb, the number of impulse trains of Fig. 2 being increased accordingly.

The operation of the systemfforselectinga free circuit in a desired group will :now be explained. When the device is seized for use, the contacts cI and x2 are closed. The mobile contact sc is moved in any desired manner not shown, on to `one of the contacts PtI to Pf3, to determine the group of circuits in rwhich selection is to bemade; it will be assumed that schas been moved on to contact Pt2 and that consequently the impulses `qZare sent on the wire MW.

It willfbe assumedthatthe device has been put into use just before the impulses pI and PI are generated. When the rst `qpI impulse is generated, the potential vof 100 v. on thetest wires 'of the No. 1 circuits of all `,the groups is replaced by afpotential of -50 v.

The only yone of the Va tubes which has the (pI impulses connected Vto its control grid is VaI, but fat the instant of the @I impulsethe `MW wire has 100 volts on it, since the (p2 impulse has not yet been generated. 'Current will therefore ow ythrough resistance Rhal and the potential on the control electrode will be -100 volts, the same potential that is on the MW wire. The control electrodes of tubes Va2 andVa3 have -100`volts on them.

Le't us consider tube VbI, since the impulse -PI coincides in time with rpl, a potential of v-5I) v. issent from impulse PI generator to the rectiiler Rcubl and, if the iirst line of group No. 1 isfree, 'that is to say, BCII closed, -50 v. vwill be sent 'from rpI impulse generator, via Vthe wire CII, contact BCII closed,RcI I, wire IWI, wire TWI, to the resistance Rhbl. At the same moment wire MW is'at 100 v .potentiaL and under these conditions rectier Rcgbl is conductive andcurrent will flow from wire TWI viaRhbI ,'RcgbI-to 'the source e2; the drop of lpotential in resistance Rhbl maintains the control electrode of VbI yat -100 v. and said tube cannot be ionized.

The -100 V. potential is sent to the control electrode of tube Vb2, via resistance RhbZ, via TW2, IW2, andthe No. 2 circuit of any group .not busy, ksince all of these free 'circuits have 100 v. on them at this time. The rectiers `Rcgb2 and Rcub2 `have 100 v. on them, but

ionized because `of the polarity fof tthe recttlers. Similarly the potential 'of the control electrode idf Vb3fi`s;maintainedat -100 v. f

Impulse pI being followed by impulse p2 from the lqofl generator, -50 volts is now applied to the MW` wire :from the p2 generator over P152 and Sc. The only'VcL tube with impulse p2 applied to its control electrode circuit is Va2. `Since -50 volts lis .applied to the rectifier Rcga2 from the MW .wire and to the resistance Rha2, no current will :flowthrough Rha2 and the control electrode will beraised to -'50 volts potential. This res tube Val Current then ows from ground, through :rel-ay RaZ, "anode and cathode discharge gap'of Vri2, 'contact czvl closed, resistance RI, battery to ground. The tube Va2 is maintained fired 'and the dropin potential across resistance RI klowers 'the potential on the cathodes of tubes "VaI `and'VaiI `so that these tubes can no longer fbe ionized. The -50 v. potential is also sent, -assurriingthe rst line of group No. 2 to be free, to fresistance Rhb'I, through C2I, contact BCZI closed, rectifier RC2I, wire IWI, wire TWI. The -50 v. .potential is simultaneously received from ywire-MW onrectier Rcgbl and directly on rec- 'tierRcubI from'the PI generator. Under these :conditionsy since both'rectifiers are blocked, tube Vbl will operate, and cause the holding of relay RbI. The ow of current in the circuit: earth, 4relay Rbl, anode'an'd-cathode of VbI, and contact c2, resistance R2, battery B2 maintains on the one hand the tube VbI red at the end of the reception of the impulse e2 and on the other hand causes a drop of potential in the resistance .R2 .which appliesthe cathodes of Vb2 and Vb@ to such a potentialthat said tubes can no longer be fionized. Itwill be noted that although a potential of '109 v. issent in each time unit to two of the -three' test'wiresin parallel CII, C2I, C3I-CI2, i022, C32 -and'CI3, C23, C33, the potential of -50 iv. receivedon the third test wire is effectively f R021, to Reza, Real to Rees inserted in the circuit for connection of each of the test wires of the circuit to the wires IW. If all'the circuits are free, the -50 v. potential is effectively transmitted to all the wires IWI, IW2, IW3 for the different impulses el, p2, e3; if certain circuits are busy, the contact BC associated with said circuits s-opened, and the corresponding impulse cannot be received on wire IW.

If circuit C2I were busy, the tube VbI could not operate during the reception ofthe impulse p2 `because there would be no -50 volts on the resistor Rhbl. Similarly it cannot during reception of the impulse p3, which follows it, since the potential of v. would then be received on the wire MW. During the reception of the cycles of impulses corresponding to the impulses 1PZ and P3 it cannot operate, since 100 V. is .then applied to the rectier Rcubl. If the circuit :C22 is free, .at the time of the simultaneous Areception of impulses p2 and P2, tube Vb2 will operate. If the circuit C22 is busy the circuits 'connected to the wire IW3 will be tested during the reception of limpulse P3 and if circuit C23 :is free tube Vb3 Will operate.

It will be assumed that tubes Va2 and Vbl have operated causing relays RaZ and Rbl to be held. Earth is'then connected via make vcontacts RaZI and RbIZ on the outlet 4 in the l second group of outlets. `:.even lif they had -50 v., the 'tube cannot be "115 lf'to effect the desired control or signalling.

This circuit can be used It will be seen that if it is desired to select a free circuit in the rst group, the switch Sc will be set on Ptl and Val will operate; if it is desired to select a free circuit in the second group, Sc will be set on Pt2 and VaZ will operate; if it is desired to select a free circuit in the third group, Sc will be set on Pt3 and Va3 will operate. It will also be seen that the selection of a particular free circuit in the selected group will determine which of the tubes Vbl to 3 will operate. Thus the operated Vb tube will be an indication of which circuit in a group has been selected.

Arrangements may be provided to connect in addition to a source p, one of the impulse sources PI, P2, P3 to the marking wire MW, by inserting a resistance in the circuit for connection to the wire MW of the source c and a rectifier in the circuit for connection of source P to the wire MW or vice versa. In this case, the device makes it possible to test a circuit in a particular group since the only tube directly connected to the source P connected to the wire MW is able to operate.

If the test device is placed at a certain distance from the circuits to be tested, it is desirable to reduce the number of interconnecting wires of the two parts of the system. This can be done by replacing the wires shown in dotted lines TWI, TW2, TW3 for individual connection of the tubes VbI, Vb2, V113, to the Wires IWI, IW2, IW3, by the common Wire TW, shown in continuous lines. In this case, the connections of the wires IW to the wire TW are respectively effected via resistances and rectiiiers Rhpl, RcpI-Rhp2, Rcp2--Rhp3, Rcp3. Furthermore, the impulse sources PI, P2, and P3 are respectively connected to the wires IWI, IW2, IW3 via rectifiers RdpI, RdpZ, Rdp3 and resistances Rhpl, RhpZ, Rhp3. In these conditions the impulses received on the wire IWI will only be received on the wire TW for the duration of one impulse PI and can, owing to this, only cause the operation of the tube Vbl. Similarly, the impulses received on the wires IWZ and IW3 can only respectively cause the operation of tubes VbZ and V173.

Of course it would be possible without departing from the scope of the invention to replace the cold cathode tubes by any device capable of causing a switching action when a particular potential is applied to its control circuit, in the same way that it is possible to choose for the different potentials such values that the switching device would operate in certain conditions.

What is claimed ist l. An arrangement for selecting a circuit in one of a plurality of circuit groups, comprising a plurality of sources of pulse trains, arranged in two groups with the pulses of the iirst group of sources having a repetition rate which is a multiple for the repetition rate of the pulses of the second group of sources, the pulse trains of each group having diiierent time positions within the group, the time duration of all pulses in a group being the same but the time duration of each pulse of the second group being sufiicient 'to encompass a complete cycle of the pulse trains of said first group, means for connecting a different one of said rst group of sources of pulse trains to each group of circuits, a plurality of coincidence trigger devices, each having a plurality of inputs and adapted to operate only when voltages at least as great as said pulses are applied simultaneously to all said inputs, said devices being arranged in two groups, the first group having a number of devices equal to the number of circuit groups and corresponding respectively to said circuit groups, the second group having a number of devices equal to the number of circuits in a group and corresponding respectively to the circuits of a group, means for selectively applying pulse trains from said first group of sources to one input of each of said devices, means ier applying pulse trains from said first group of sources respectively to second inputs of the devices of said first group, means for applying pulse trains from said second group of sources respectively to second inputs of the devices of said second group, means for connecting third inputs of the devices of said second group respectively to corresponding circuits of each group of circuits, a plurality oi' control circuits corresponding to the circuits of said groups, and means controlled by the combination of devices operated for energizing a selected one of said control circuits.

2. An arrangement, according to claim 1, in which the trigger devices comprise electronic discharge paths, each path having an anode, a cathode, and a control electrode, the inputs being connected to the control electrodes, there being one input for each pulse train applied, one of said inputs including a resistance and the others including rectiiiers poled so that current flowing through said resistance between said inputs will produce a drop in potential on said control electrode.

3. An arrangement, according to claim 2, in which individual leads are provided for connecting the third inputs of the devices of the second group to corresponding circuits of each group of circuits.

4. An arrangement, according to claim 1, in which a single lead is provided for connecting all the third inputs of the devices or the second group to corresponding circuits of each group of circuits, the connection of each group of correspending circuits to said single lead comprising a resistance and a rst rectier in series therewith, the rectifier being connected to the single lead and poled in a direction so that current can flow towards said devices, an auxiliary lead including a second rectifier connected to the junction of said resistance and rst rectiiier, with said second rectifier so poled that current can flow out of said auxiliary lead, and means for applying pulse trains from said second group of sources respectively to said auxiliary leads.

5. An arrangement, according to claim 4, in which individual means is provided for each circuit for breaking the connection between it and a third input of the second group of trigger devices When the circuit is in a predetermined condition.

6. An arrangement, according to claim 5, in which the means for energizing a selected one of the control circuits comprises a plurality of relays, one connected to each device in the first and second groups of devices and arranged to operate when said device operates, the control circuits including contacts of said relays.

'7. An arrangement, according to claim 1, in which individual means is provided for each circuit for breaking the connection between it and a third input of the second group of trigger devices when the circuit is in a predetermined condition.

8. An arrangement, according to claim 1, in which the trigger devices comprise electronic discharge paths, each path having an anode, a cath-` ode, and a control electrode, the inputs being connected t0 the control electrodes, there being electrode, and in which the means for energizing a selected one of the control circuits comprises a plurality of relays, one connected to each device in the rst and second groups of devices and arranged to operate when said device operates, the 10 2,484,612

control circuits including contacts of said relays.

MARTINUS' DEN HERTOG.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,338,242 Haigh Jan. 4, 1944 2,452,578 Kruithof et a1 Nov. 2, 1948 2,454,809 Kruithof et a1 Nov. 30, 1948 Dehn et al Oct. 11, 1949 

